Slitting roll

ABSTRACT

A slitting roll for slitting an advancing sheet of elongate flexible foam material or the like to form a pattern of incisions therein. The roll includes a plurality of ribs of inverted Vshaped profile in the surface thereof, the ribs being disposed along a small helix angle with respect to the axis of the roll. A series of spaced radial apertures are formed in the ribs to define a plurality of spaced cutting blades, and the roll comprises a series of coaxial roll sections fixedly assembled onto a common supporting shaft.

'United States Patent Currie et al. July 1, 1975 1 SLITTING ROLL2,224,668 |2/|940 Christian 83/672 [76] Inventors: Grover C. Currie, 901Ridgecrest D12, N.E., Lenoir, N.C. 28645; 3: 2 :1 5 7/ 974 Brendan L.Doll, Box 8, Patterson. 2866 Primary Examiner-D0nald R. Schran [22]Filed: July 15, 1974 Attorney, Agent, or Firm-Parrott, Bell, Seltzer,Park 21 Appl. No.: 488,437

Related US. Application Data 57] ABSTRACT [62] Division of Ser. No.343,677, March 22, I973, Pat.

3321621 A slitting roll for slitting an advancing sheet of elongateflexible foam material or the like to form a pat- 52 us. Cl. 83/672;83/342; 83/678; tern of incisions thereih- The roll includes a plurality33 3 of ribs of inverted V-shaped profile in the surface 5| 1m. Cl. 826d1/32; B261 1 20 thereof. the ribs being disposed along a Small helix[58] Field at Search 83/672, 678, 342, 346, angle with respect to theaxis of the A serifis of 33 2 spaced radial apertures are fonned in theribs to define a plurality of spaced cutting blades, and the roll 5References Cited comprises a series of coaxial roll sections fixedly as-UNITED STATES PATENTS sembled onto a common supporting shaft.

1,5 I 1,054 l0/l924 Duncan 6. 83/346 7 Claims, 8 Drawing FiguresSLITTING ROLL This application is a division of application Ser. No.343,677 filed Mar. 22, 1973, and now US. Pat. No. 3,823,623.

The present invention relates to a slitting roll which is adapted foruse in processing elongate foam sheet material to form the same into anopen cushioning material to be used in packaging and protecting articlessusceptible to damage during handling and shipment thereof.

The prior US. patent to Martin Doll, US. Pat. No. 3,642,967, and ofcommon assignee, discloses a method of producing a net-likethermoplastic foam material of significant structural rigidity and whichis adapted for use in various packaging applications. The methodincludes slitting a sheet of thermoplastic foam material in a pattern ofspaced incisions, opening the incisions into lozenge-like form by aforce applied to the material transversely of the rows of incisions, andheat setting the material in the opened condition.

In order to slit the foam material in accordance with the process of theabove patent, it has been proposed to slit a sheet of thermoplastic foammaterial in a pattern of spaced incisions by passing the sheet between aslitting roll and a mating anvil roll, the slitting roll having spacedknives or cutting blades thereon to form the incisions. It has beenfound however that when it is desired to form the incisions in rowsextending laterally across the advancing web, the axially extending rowsof cutting blades on the slitting roll generate considerable chatter andvibration upon rotation in contact with the anvil roll. This not onlyresults in the rapid deterioration of the apparatus, but it alsosignificantly increases its power consumption.

Problems have also been encountered in attempting to fabricate aslitting roll having axially extending rows of cutting blades. Forexample, the slitting roll is typically about 48 inches long in order tohandle a sheet of foam material having a conventional width of about 42inches, and no satisfactory method of fabricating a roll of this lengthhas been developed. More particularly, it will be understood that thecutting blades of the slitting roll should be heat hardened to achievethe necessary wear resistance, and such heat hardening can only beaccomplished after the cutting blades are formed since a milling toolwould not be able to cut the teeth in a hardened roll. However, a rollof the above length cannot be heat hardened without significantdeformation, and such deformation would upset the orientation of therows of cutting blades, thus making it impossible to finish grind orsharpen the hardened blades.

It is accordingly an object of the present invention to provide aslitting roll which may be used with a mating anvil roll to efficientlyslit a longitudinally advancing sheet of elongate foam material inlaterally extending rows of incisions and which avoids the disadvantagesheretofore encountered.

It is another object of the present invention to provide a method ofefficiently fabricating a slitting roll of the described type and whichavoids any problem of deformation during heat treatment.

These and other objects and advantages of the present invention areachieved in the embodiment illustrated herein by the provision of aslitting roll which comprises a plurality of adjacent ribs on thesurface thereof, the ribs being curved along a small helix with respectto the central axis of the roll. A plurality of equally spaced, radialapertures extend along the length of each rib to define a plurality ofrows of spaced cutting blades and with the blades of adjacent rows beingin staggered relationship. The roll is fabricated by a method whichincludes the steps of forming the ribs in the surface of each of aplurality of cylindrical tubular roll sections, drilling a series ofequally spaced radial apertures along the length of each rib of eachroll section, heat hardening the sections, and then fixedly assemblingthe same onto a common supporting shaft in abutting end to end, coaxialrelationship.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds, when taken in connection withthe accompanying drawings, in which FIG. I is a block diagram of amethod of fabricating a slitting roll in accordance with the presentinvention;

FIG. 2 is a fragmentary perspective view illustrating the step offorming the helical ribs on a roll section by means of a rotary cuttingwheel;

FIG. 3 is a fragmentary perspective view illustrating the step ofdrilling spaced radial holes in the ribs to form rows of spaced cuttingblades;

FIG. 4 is an exploded perspective view illustrating the step ofassembling roll sections onto a common shaft;

FIG. 5 is a fragmentary perspective view illustrating the step ofsharpening the profile of the ribs by means of an axially translatedgrinding wheel;

FIG. 6 is an enlarged elevation view of the portion of the surface ofthe slitting roll shown in the block 6 of FIG. 5;

FIG. 7 is a section view taken substantially along the line 7--7 of FIG.6;

FIG. 8 is a transverse section taken perpendicular to the axis of theroll and substantially along the line 8--8 in FIG. 6.

Referring more specifically to the drawings, a substantially completeslitting roll embodying the features of the present invention is shownat 10 in FIG. 5. The illustrated roll may be employed for example in anapparatus of the type disclosed in copending application Ser. No.343,678 by the present inventors filed Mar. 22, 1973 and entitledAPPARATUS FOR PROCESS- ING FOAM SHEET MATERIAL. Briefly described. theapparatus disclosed in the referenced copending application includesslitting means comprising a slitting roll and a mating anvil rollforming a nip therebetween and through which the advancing sheetmaterial is passed such that a plurality of laterally extending rows ofincisions is formed in the sheet material.

The surface of the slitting roll of the present invention is generallycylindrical to define a central axis 11, and comprises a plurality ofribs 12 formed therein, the ribs being curved along a small helix withrespect to the axis 11 as indicated by the angle A in FIG. 6. As bestseen in FIG. 8, the ribs have an inverted V-shaped profile, and aplurality of equally spaced, radial apertures 14 extend along each rib.The apertures of adjacent ribs are in staggered relationship to define aplurality of rows of spaced cutting blades of substantially equal lengthand spacing, and with the blades in adjacent rows being staggered. Thusthe foam material drawn through the nip formed by the slitting roll andmating anvil roll is slit in a pattern of spaced apart laterallydirected rows of spaced incisions and with the incisions in adjacentrows being in staggered relationship.

The particular helix angle A employed can vary somewhat, but the angleshould be sufficient to permit at least three of the rows of cuttingblades to simultaneously contact the anvil roll since this has beenfound desirable in preventing chatter. Also, the angle should not be sogreat as to cause a readily visible inclination in the lines ofincisions in the finished foam material. In addition, too large a helixangle may cause difficulty during any subsequent drawing or openingoperation on the foam material since the inclined incisions may causethe material to skew in the drawing rolls. In this regard, it has beenfound that in most applications the helix angle A should lie betweenabout 2 and In such case, the rows of incisions formed in the foammaterial would extend between about 80 and 88 to the direction ofadvance. A helix angle of this order has been found to be sufficient toavoid the chatter or vibration associated with cutting blades whichparallel the axis of the roll, and the angle of the rows of incisions isnot readily apparent in the finished product and does not adverselyeffect subsequent processing.

The roll 10 may be fabricated by the method illustrated in FIG. 1.Initially, a plurality of axially directed channels are milled in thesurface of each of a plurality of nonhardened, steel, tubular rollsections 16 by means of a rotary cutting wheel 18 or the like to definethe ribs 12 therebetween. As illustrated, the cutting wheel 18 has aV-shaped cutting edge profile having about a 60 included angle, and thechannels are positioned immediately adjacent each other such that theribs 12 have a relatively sharp, inverted V-shaped profile also of abouta 60 included angle. Each roll section I6 is typically about 8 inches inlength, 4% inches in outside diameter, and 3 /4 inches in insidediameter. Such roll sections may have about 75 to 110 ribs formed in thesurface thereof.

In order to form the ribs along the desired helix, each roll section 16may be slowly rotated on its axis as the cutting wheel 18 is linearlytranslated along the length thereof. After one channel is formed, theroll section is forwardly indexed about its axis such that the wheelforms a new channel parallel to and immediately adjacent the previouschannel. As will be apparent, the extend of the forward indexing ispredetermined such that a desired number of complete channels (and thusribs 12) is formed about the circumference of the roll. A machineadapted to form the ribs in the above manner, as well as sharpen thesame as hereinafter further described, is disclosed in copending US.application Ser. No. 343,679 by Brendan Doll filed Mar. 22, 1973 andentitled APPARATUS AND METHOD FOR FORM- ING SLITTING ROLL.

When the formation of the ribs is complete, a series of equally spaced,radial apertures is drilled through each rib employing a conventionaldrill press 20. The spaced apertures extend along the length of eachrib, and the apertures in adjacent ribs are staggered as best seen inFIG. 6. Also, the apertures are equally spaced from the adjacentapertures in adjacent ribs such that the apertures of alternate ribsdefine a plurality of circumferential rows of apertures (e.g., alongline 88 of FIG. 6). Each of these circumferential rows of apertures liesin a plane perpendicular to the axis of the roll section, and the rowsare equally spaced from each 6 other. For the reasons hereinafterexplained, the circumferential rows are positioned at a predetermineddistance with respect to the ends 22 of the roll sections.

With roll sections having the dimensions described above, the apertures14 are typically spaced about 1% inches from center to center along theribs, and the apertures are about A inch deep. Also, the diameter of theapertures may be between about Va and 3/16 inches, depending upon thelateral width of the rib.

After formation of the apertures 14 in a plurality of roll sections 16,the sections may be heat hardened to about 62-68 Rockwell C hardness.This may be accomplished in a conventional oven in a manner well knownin the art. The ends 22 of each roll section may then be machinefinished by grinding or the like to form a finished flat end surfacewhich lies perpendicular to the axis of the roll to facilitate end toend engagement as hereinafter further explained.

Next, the roll sections 16 are fixedly assembled onto a commonsupporting shaft 24 in abutting end to end, coaxial relationship to forma joint 25 as seen in FIG. 6. As part of this process, the ribs of eachroll section are aligned with the ribs of adjacent sections. Moreparticularly, the predetermined spacing of the circumferential rows ofapertures from the ends 22 permits the ribs in one roll section to bealigned with the proper ribs in the adjacent roll section such that thespacing of the apertures continues in an uninterrupted, equally spacedpattern aross the end to end joint 25 to define axially directed rows ofequally spaced cutting blades which extend from end to end of thecompleted roll I0, and with the blades of adjacent rows being instaggered relationship.

The diameter of the supporting shaft 24 is such as to closely receivethe roll sections and the roll sections may be fixed thereto by means ofan adhesive 26. Suitable adhesives for this purpose are known in theart, and one is sold under the trademark Loctite by the LoctiteCorporation of Newington, Conn. Also, the ends of the supporting shaft24 may include a threaded portion 28 and mating sleeve 29 to precludeaxial movement of the sections on the shaft 24 while the adhesive sets.

As a final step in fabricating the roll I0, the profile of each rib maybe sharpened by a suitable grinding wheel 32 as seen in FIG. 5. Thegrinding wheel 32 has a V-shaped cutting edge profile conforming to thatof the channels formed by the rotary cutter l8, and the wheel islinearly translated along the length of the roll as the roll is rotatedabout its axis in a manner similar to that described above with respectto the action of the rotary cutter 18. The sharpening operation may beemployed not only in the initial fabrication of the roll, but also aftera period of use to resharpen the cutting blades.

In the drawings and specification. there has been set forth a preferredembodiment of the invention, and although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation.

That which is claimed is:

I. A slitting roll suitable for slitting an advancing sheet of elongateflexible foam material or the like to form a pattern of spaced apartlaterally directed rows of spaced incisions in the web and with theincisions in adjacent rows being in staggered relationship, said rollcomprising a cylindrical peripheral surface defining a central axis andincluding a plurality of adjacent ribs formed therein, said n'bs havingan inverted V-shaped profile and being curved along a helix such that atleast three ribs are adapted to simultaneously contact a mating anvilroll or the like, and

a plurality of equally spaced, radial apertures extending along thelength of each rib and with the adjacent apertures of adjacent ribsbeing in staggered relationship to define a plurality of rows of spacedcutting blades and with the blades of adjacent rows being in staggeredrelationship.

2. The slitting roll as defined in claim I wherein said apertures inalternate ribs define a plurality of circumferential rows of aperturesand with each row of apertures lying in a plane which perpendicularlyintersects said central axis of the roll.

3. The slitting roll as defined in claim 2 wherein said circumferentialrows of apertures are equally spaced from each other.

4. The slitting roll as defined in claim 1 wherein the V-shaped profileof said ribs has an included angle of about 60 and a sharp upper edge.

5. A slitting roll suitable for slitting an advancing sheet of elongateflexible foam material or the like to form a pattern of spaced apartlaterally directed rows of spaced incisions in the sheet and with theincisions in adjacent rows being in staggered relationship, said rollcomprising a cylindrical supporting shaft defining a central axis,

a plurality of tubular roll sections fixedly assembled onto said shaftin abutting end to end relationship, said tubular roll sections defininga cylindrical peripheral surface coaxial with said central axis, saidperipheral surface including a plurality of adjacent ribs of invertedV-shaped profile formed therein to define a sharp cutting edge, saidribs covering the entire peripheral surface and being curved along ahelix extending between about 2 and 10 with respect to said centralaxis, and

a plurality of equally spaced, radial apertures extending along thelength of each rib and with the adjacent apertures in adjacent ribsbeing in staggered relationship to define rows of spaced cutting bladeswith the blades in adjacent rows being staggered.

6. The slitting roll as defined in claim 5 wherein said roll sectionsare fixedly assembled to said supporting shaft by means of an adhesive.

7. The slitting roll as defined in claim 6 wherein said apertures inalternate ribs define a plurality of equally spaced, circumferentialrows of apertures and with each row of apertures lying in a plane whichperpendicularly intersects said central axis.

1. A slitting roll suitable for slitting an advancing sheet of elongateflexible foam material or the like to form a pattern of spaced apartlaterally directed rows of spaced incisions in the web and with theincisions in adjacent rows being in staggered relationship, said rollcomprising a cylindrical peripheral surface defining a central axis andincluding a plurality of adjacent ribs formed therein, said ribs havingan inverted V-shaped profile and being curved along a helix such that atleast three ribs are adapted to simultaneously contact a mating anvilroll or the like, and a plurality of equally spaced, radial aperturesextending along the length of each rib and with the adjacent aperturesof adjacent ribs being in staggered relationship to define a pluralityof rows of spaced cutting blades and with the blades of adjacent rowsbeing in staggered relationship.
 2. The slitting roll as defined inclaim 1 wherein said apertures in alternate ribs define a plurality ofcircumferential rows of apertures and with each row of apertures lyingin a plane which perpendicularly intersects said central axis of theroll.
 3. The slitting roll as Defined in claim 2 wherein saidcircumferential rows of apertures are equally spaced from each other. 4.The slitting roll as defined in claim 1 wherein the V-shaped profile ofsaid ribs has an included angle of about 60* and a sharp upper edge. 5.A slitting roll suitable for slitting an advancing sheet of elongateflexible foam material or the like to form a pattern of spaced apartlaterally directed rows of spaced incisions in the sheet and with theincisions in adjacent rows being in staggered relationship, said rollcomprising a cylindrical supporting shaft defining a central axis, aplurality of tubular roll sections fixedly assembled onto said shaft inabutting end to end relationship, said tubular roll sections defining acylindrical peripheral surface coaxial with said central axis, saidperipheral surface including a plurality of adjacent ribs of invertedV-shaped profile formed therein to define a sharp cutting edge, saidribs covering the entire peripheral surface and being curved along ahelix extending between about 2* and 10* with respect to said centralaxis, and a plurality of equally spaced, radial apertures extendingalong the length of each rib and with the adjacent apertures in adjacentribs being in staggered relationship to define rows of spaced cuttingblades with the blades in adjacent rows being staggered.
 6. The slittingroll as defined in claim 5 wherein said roll sections are fixedlyassembled to said supporting shaft by means of an adhesive.
 7. Theslitting roll as defined in claim 6 wherein said apertures in alternateribs define a plurality of equally spaced, circumferential rows ofapertures and with each row of apertures lying in a plane whichperpendicularly intersects said central axis.